In recent years, wind turbines have increased in popularity as a means of electrical power generation. Wind turbines offer the advantages of relatively inexpensively generating power from a renewable energy source as well as having a low impact on the surrounding environment.
The electrical system of a wind turbine typically includes several power systems. The main power system includes the circuits and components which connect the wind turbine generator to the electrical power grid, while the auxiliary power system (also known as the low voltage distribution system) provides power to auxiliary components such as lights, security systems, electronic controls, climate controls, motors, and so forth. Typically, the auxiliary power system is fed by an auxiliary transformer which connected between the power converter and the main power transformer. In systems utilizing a doubly-fed induction generator (DFIG) and excitation converter, the auxiliary power system is typically fed by an auxiliary transformer connected between the junction of the DFIG and excitation converter, and the main power transformer.
When the turbine is generating power, the auxiliary power system is powered by the electricity generated by the wind turbine. Conversely, when the turbine is not generating power, auxiliary power is still required to monitor the electrical system, as well as to power the auxiliary components. In such situations, power is provided to the auxiliary system by back-feeding electricity from the electrical power grid.
When maintenance personnel need to perform work on the wind turbine, the generator is shut down and main power transformer is disconnected from the electrical power grid. This de-energizes the power generating system between the turbine generator and the power grid, thereby eliminating the risk of electric shocks from energized wires, assemblies, or components in the nacelle. However, as a result, no power remains available to feed the auxiliary systems of the wind turbine. A solution for powering the auxiliary systems of a wind turbine while the main transformer is disconnected from the power grid is therefore desired.